The invention relates to a converter for converting mechanical energy into hydraulic energy and to a robot implementing said converter. The invention can be particularly used in the production of humanoid robots in which autonomy is to be improved.
Such robots are equipped with actuating mechanisms that allow the different parts of the robot to be moved. These mechanisms connect a power source providing mechanical energy such as, for example, an electric, hydraulic or pneumatic motor, to a load. In other words, an actuating mechanism transmits mechanical power between a motor and a load.
An essential parameter of an actuating mechanism is its transmission ratio which is chosen so as to adapt a nominal working point of the load to that of the motor. In a known actuating mechanism in which the transmission ratio is constant, formed for example from a set of gears, the choice of the ratio is limited to discrete values and changing the ratio necessitates complicated devices such as a gearbox to adapt the transmission ratio. Now, in robotic applications, the working point of the loads is generally highly variable. If the reduction ratio is constant, this means that the motor must be dimensioned for the most unfavorable circumstances in which the load is used.
Devices exist which allow the transmission ratio to be varied continuously but these are complicated and their performance is often poor. Belt speed reducers are known, for example, whose transmission ratio is varied as a function of the speed of the motor by means of inertia masses.
The above-described actuating devices are bulky, heavy and complex, which is disadvantageous for robotic applications.
Moreover, of the abovementioned motors, electric motors are well suited only to high speeds and low torques. In robotic applications, the opposite situation is common: low speed and high torque. The use of electric motors for low speeds entails high reduction ratios that are thus complicated to achieve.
As is known, in robotic applications, a central hydraulic power unit is used that is connected to different joints to be driven by lines transporting a pressurized fluid. When the robot includes a large number of actuators, the network of lines becomes complex. Moreover, the hydraulic power unit must provide to all the joints the maximum pressure required by the joint that is subject to the greatest demand.